read arch.list

tests/profile/read_mock_profile.rs

@@ -18,6 +18,14 @@ fn main() {
 
     assert_eq!(global_package_mask, vec!["app-editors/vim"]);
 
+    assert_eq!(
+        repo.arch_list()
+            .iter()
+            .map(|arch| arch.get())
+            .collect::<Vec<_>>(),
+        vec!["amd64", "aarch64"]
+    );
+
     let profile = repo
         .evaluate_profile("gentoo-desktop")
         .expect("failed to evaluate profile");